The present invention relates generally to air blaster or air accumulator devices adapted to periodically discharge air to facilitate the flow of bulk materials. Such devices, more precisely referred to as blast aerators, are believed to be relevantly classified in U.S. Class 222, Subclasses 1 and 3.
It is well known that in handling or processing bulk loads such as concrete, grain, wood chips or other materials the hoppers or storage bins involved can often become jammed or temporarily blocked. Such materials usually tend to cake or congeal during bulk processing. For example, flow problems are quite common with the conventional, generally conically shaped hoppers in widespread use. While bulk flow problems may of course be temporarily remedied by physically vibrating the hopper or container to shake the materials loose, not all materials may be dislodged in this manner. For example, large concrete bunkers may be impossible to vibrate. Materials like soft wood chips ordinarily absorb vibratory energy and must be dislodged by other methods.
In the prior art it has been suggested to dislodge bulk materials to promote smooth material flow by periodically introducing high pressure air blasts into the jammed container. Typically blast aerators are physically mounted exteriorly of the hopper, and introduce periodic high pressure charges of air to dislodge the material. Examples of prior art technology believed most relevant to the present invention may be seen in the following previously issued U.S. Pat. Nos. 3,915,339; 4,197,966; 3,651,988. Other relevant blast aerator technology is disclosed in Great Britain Pat. Nos. 1,426,035 and 1,454,261; West German Pat. No. 2,402,001; and Austrailian Pat. No. 475,551. Less relevant prior art, in which pressurized air is utilized to project tennis balls or the like, may be seen in the following previously issued U.S. Pat. Nos. 2,935,980; 1,379,403; 2,182,369; and 2,525,082.
Quick release aerators of the type disclosed in the above mentioned patents have gained widespread acceptance as useful remedies for bulk flow problems. However, because of a variety of mechanical weaknesses inherent in previous aerator construction techniques, mechanical efficiency and reliability has been questionable. More importantly, the periodic high pressure, high volume air discharges generated by air blaster subject internal parts to extreme stresses which promote component failure. As will be readily appreciated, failure of critical structural parts, primarily the piston housing members employed by such devices, may result in severe injury to operating personnel. Even where injury is avoided, aerator component breakdown may severely limit operational efficiency of the bulk flow system on which the aerator has been installed. Component breakdown has been found to result at least in part from the hitherto multi-piece construction of the piston housing assembly or blast output pipe.
Piston wear and tear is another problem. In prior art designs that portion of the piston utilized to create a seal also functions as the working surface upon which tank pressure works to force the piston to its "blast" position. Blasting is initiated, for example, by venting the cavity formed between the piston rear and the discharge pipe assembly in which it is housed. It is thus desireable to provide a piston sealing surface separate from its blast actuation surface.